Safety needle with positive flush

ABSTRACT

A safety needle device and positive flush mechanism for use with a vascular access port. In one embodiment, the combination needle assembly includes a needle, a body and a base, the body being collapsible to expunge fluid therefrom as the needle is withdrawn from a vascular access port. In another embodiment, the combination needle assembly includes a needle, a housing and a reservoir, the housing squeezing the reservoir to expunge fluid therefrom as the needle is withdrawn from the port. In another embodiment, the needle assembly includes a compression plate and balloon extension, the compression plate forcing fluid out of the balloon extension as the needle is withdrawn from the port. In all embodiments, the needle assembly is configured to provide a positive flush to overcome negative pressures in the vascular access port, while also providing a locking mechanism to prevent accidental needle sticks.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and moreparticularly to needle safety devices and positive flushing mechanisms.

Implantable vascular access systems are used extensively in the medicalfield to facilitate the performance of recurrent therapeutic tasksinside the body of a patient. Such vascular access systems generallyinclude an implantable vascular access port attached to a vascularcatheter. A typical vascular access port has a needle-impenetrablehousing that encloses a fluid reservoir that is accessible from theexterior of the access port through a needle-penetrable elastomericseptum.

The entirety of the system, both the vascular access port and thecatheter attached thereto, is implanted in the body of a patient. Thedistal tip of the catheter is disposed at a predetermined location wheretherapeutic activity is to be effected. Once the vascular access systemis implanted, the tip of a hypodermic needle can then be employedselectively and repeatedly to access the fluid reservoir of the accessport by penetrating the skin at the implantation site for the accessport and then by being advanced through the septum of the access portitself.

While often times syringe-type devices are utilized for vascular accessports in acute or short-term situations, a special type of device isutilized for longer term infusion therapy. Such an infusion assemblydevice generally consists of a needle and wing assembly that lies flatagainst the skin in an insertion position, the needle having a proximalend attached to a wing assembly that is in angular relation to theneedle shank, the angle being approximately 90°. As mentioned, when thislonger term needle device is inserted into the vascular access port, itlies flat against the patient's skin and is adhered thereto asdescribed, for example, in U.S. Pat. No. 4,710,176 to Quick.

With respect to the needle tip of the needle used in infusion assembliesfor vascular access ports, a non-coring configuration is generallyutilized due to repeated entry of the needle into the septum of thevascular access port. When the tip of a hypodermic or other traditionalneedle advances through the septum, coring occurs if any portion of theseptum material is forced inside the shaft of the needle through theopening in the tip thereof. That portion of the septum material forcedinside a needle in this process is in effect severed from the rest ofthe body of the septum material. Such septum coring produces small,detached particles of the septum that are likely to enter the fluid thatis infused by the implanted vascular access system into the vascularsystem of the patient. These particles can obstruct fluid flow throughthe outlet stem of the vascular access port, or if escaping through theoutlet stem of the vascular access port, can become trapped in thecardiovascular system of the patient.

In addition, septum coring produces small passageways through the bodyof a septum. On occasion these passageways extend entirely through theseptum, from the exterior thereof to the fluid reservoir inside thevascular access port. The inwardly directed forces imposed on theinstalled septum by the housing of a vascular access port shouldinitially urge the material of the body of the septum inwardly uponitself to close such passageways after the shaft of the needle iswithdrawn therefrom. Nonetheless, continued coring eventually leads tovarious forms of septum failure that cannot be overcome by such inwardlydirected forces. The material continuity of the septum is increasinglycompromised, resulting in crumbled areas of the septum matrix.Eventually, leakage of fluid can be expected through the septum from thefluid reservoir in the vascular access port. Once such fluid escapes tothe exterior of the vascular access port, necrosis will occur of thetissue surrounding the subcutaneous pocket in which the vascular accessport is implanted, causing many undesirable consequences. Therefore,non-coring or Huber needles are preferably used in conjunction withinfusion assemblies for vascular access ports. These needles, incontradistinction to the standard or traditional hypodermic needlespierce the septum like a knife, facilitating the resealing thereof sothat the aforementioned problems are largely averted.

As with any needle-type device, there exists the problem of inadvertentneedle sticks, which generally occurs when the needle-type device iswithdrawn from the patient prior to appropriate disposal thereof. Ofcourse, inadvertent needle sticks introduce a variety of concerns due tounwanted transmission of blood from the patient to the medicalpractitioner. Inadvertent needle sticks can occur because ofcarelessness on the part of the medical practitioner or due to accidentsin the handling of devices with exposed needle tips. With respect toHuber needles specifically, needle stick accidents can occur due todifficulty in removal as well. This difficulty results from theconfiguration of the Huber needle, which gets hooked into the portmaking it difficult to remove. Increased pulling force on behalf of themedical practitioner to dislodge the needle from the port results inless control over the tip of the needle when freed from the port,causing the inadvertent needle stick.

To address the inadvertent needle stick problem in winged infusionassemblies, such as those described herein, various safety devices havebeen designed to encase the needle after it is withdrawn from the port.One such safety device is described in U.S. Pat. No. 5,755,694 to Camus.Camus discloses a needle base disposed over a segment of the needle atits proximal end, comprising two generally flat wings made of flexiblematerial with one hinge connecting each of the wings to the needle base.Upon removal of the needle from the patient the wings flex against amoveable member that keeps them adjacent the needle until the needle iscompletely removed from the skin of a patient after which the wingssurround the needle to prevent the tip from making contact outside ofthe needle base.

Another type of safety device is described in U.S. Pat. No. 5,951,522 toRosato et al., in which the particular configuration of the Huber needleis also taken into account. Rosato et al. discloses a safety enclosurecomprising a wing assembly mounted to the aft end of a angled Huberneedle, the wing assembly having a configuration consisting of either asingle integral member having a plurality of spaced apart fold lineswhich divide the member into a plurality of interconnected panels, or apair of wing members mounted in a scissors-type arrangement. In eachembodiment, when the medical practitioner removes the needle from thepatient, the wing assembly closes around the needle and locks together,encasing it therein.

While many advancements have been made in the area of needle devices foruse with vascular access ports, such as those described herein, thereremains a heretofore unsolved problem related to removal of the needledevice from the vascular access port. When the needle is insertedthrough the septum, it occupies a volume equal to the externaldimensions thereof present in the fluid reservoir positioned underneaththe septum. When the needle is removed from the vascular access port,the needle volume is evacuated without replacement, causing anequivalent volume of venous fluid to be drawn into the catheter tip atthe distal end thereof. This infiltration of venous fluid is suspectedto cause or contribute to thrombus formation at the catheter tip, whichblocks the flow of fluid therethrough and results in early removal ofthe port and catheter from the patient. Early removal is costly,invasive and time-consuming and otherwise extremely undesirable.

One solution to this problem of unwanted venous fluid being drawn intothe catheter tip has been to implement a positive flushing technique asthe needle is withdrawn. This technique generally consists of themedical practitioner inserting a syringe into the port and injecting asolution such as heparin while simultaneously withdrawing the needle.This technique, however, can be quite cumbersome and complicated and infact may require more than one operator, as many of the infusion setsfor use with vascular access ports require two hands to withdraw. Forthese reasons and others, it is known that a significant population ofmedical practitioners forego the practice of the described techniquedespite the adverse consequences that could result, as outlined herein.Therefore, it would be desirable to incorporate a flushing mechanisminto a needle infusion set for use with a vascular access port so thatflushing upon removal of the needle from the septum is assured.

In particular, it would be desirable to incorporate a positive flushingmechanism into various needle assemblies, one of which being an improvedinfusion needle assembly for use with a vascular access port that alsoprovides a safety feature to prevent needle sticks.

BRIEF SUMMARY OF THE INVENTION

Accordingly, a primary object of the present invention is to provide aneedle assembly that incorporates a positive flushing mechanism. It isanother object of the present invention to provide an improved needleassembly that will prevent accidental needle sticks upon the removal ofthe needle from the patient. It is yet another object of the presentinvention to provide an improved needle assembly that is configured toaccount for the geometry of a Huber needle. It is still another objectof the present invention to provide a method of withdrawing a safetyinfusion set from a patient. It is a further object of the presentinvention to provide a method of positively flushing a vascular accessport during withdrawal of the safety infusion set from a patient.Various other objectives and advantages of the present invention willbecome apparent to those skilled in the art as more detailed descriptionis set forth below.

In accordance with the present invention, several embodiments aredescribed, which may be improvements to prior art needle assemblies ormay be novel infusion needle set embodiments heretofore undisclosed. Asused herein, the following terms have the following meanings:

“Vascular access port” refers to a port having a needle-impenetrablehousing enclosing a fluid reservoir that is accessible from the exteriorof the port through a needle-penetrable elastomeric septum.

“Positive flush” refers to the action of a fluid being sent through aneedle as the needle is being removed from a reservoir of a vascularaccess port or similar device so that the fluid replaces the volume thatthe needle occupies within the reservoir. It should be noted that theactual amount of fluid being sent through the needle will be greaterthan the volume of the needle in most cases.

In one embodiment of the present invention, a needle assembly isprovided, including a needle, a body and a base. The body is in the formof a collapsable male and female portion, where the collapsing actionproduces the positive flush following delivery of a drug or medicine toan implanted vascular access port. The base includes a contact patchthat lies flat against the patient's skin for delivery of the drug ormedicine and, which facilitates removal of the needle from the vascularaccess port. An arm and a hinge are attached to the contact patch, beingrespectively connected to the male and female portions of the body. Whenthe needle assembly is moved from an insertion position to a protectionposition, the collapsing action of the body flushes fluid therefromsimultaneous to the needle exiting the vascular access port, creating apositive flush and preventing any negative pressures therein. The needleassembly contains a primary and secondary locking mechanism to ensurethat accidental needle sticks are avoided.

In an alternate embodiment of the present invention, a winged assemblyis provided, including a needle, a needle housing and a collapsiblereservoir. The needle housing has an upper and lower portion that areconnected to one another. The upper portion houses the collapsiblereservoir, which is adhered thereto in a way that allows complete anduniform collapse. The proximal end of the needle is attached to thefront end of the upper portion and is fluidly connected to thecollapsible reservoir. A connector is attached to the rear end of theupper portion, also in fluid communication with the reservoir, theconnector being configured for attachment to an extension tubing set.The lower portion contains four connected panels, having lockingmechanisms associated therewith to releasably lock the winged assemblyin the insertion position and to permanently lock the winged assembly inthe protection position. When the winged assembly is moved from aninsertion position to a protection position, extensions on the lowerportion of the needle housing press against the collapsible reservoirsimultaneous to the needle exiting the vascular access port, expungingfluid therein through the needle to create a positive flush.

In another embodiment of the present invention, a needle assembly isprovided, including a needle, a handle, a wing base and a supportstructure. The handle has a left and right half which are connectedtogether around a balloon extension that is connected to the proximalend of the needle and is in fluid communication therewith, and acompression plate that is connected to legs of the support structure.The support structure is bonded to the bottom of the wing base, the legsthereof fitting through holes in the wing base. The handle is movablewith respect to the wing base and support structure for movement from aninsertion position to a protection position. The balloon extension istrapped between the compression plate and handle so that movement of thehandle upward results in compression of the balloon extension. As theballoon extension is compressed, the fluid contained therein is flushedthrough the needle as the needle exits a vascular access port to createa positive flush.

These and other embodiments, features and advantages of the presentinvention will become more apparent to those skilled in the art whentaken with reference to the following more detailed description of theinvention in conjunction with the accompanying drawings that are firstbriefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a needle assembly according to thepresent invention in the insertion position.

FIG. 2 is a perspective view of the needle assembly of FIG. 1 in theprotection position.

FIG. 3 is a perspective view of the base portion of the needle assemblyof FIG. 1 in the insertion position of FIG. 1.

FIG. 4 is a perspective view of the base portion of the needle assemblyof FIG. 1 in the protection position of FIG. 2.

FIG. 5A is a close-up cross-sectional view of the needle housing of theneedle assembly of FIG. 1 in the insertion position.

FIG. 5B is a close-up cross-sectional view of the needle housing of theneedle assembly of FIG. 1 in the protection position.

FIG. 6 is a bottom perspective view of the male portion of the body ofthe needle assembly of FIG. 1.

FIG. 7 is a top perspective view of the male portion of the body of theneedle assembly of FIG. 1.

FIG. 8 is a perspective view of the proximal end of the female portionof the body of the needle assembly of FIG. 1.

FIG. 9 is a perspective view of the distal end of the female portion ofthe body of the needle assembly of FIG. 1.

FIG. 10 is a top cross-sectional view of the needle assembly of FIG. 1in the insertion position of FIG. 1.

FIG. 11 is a top cross-sectional view of the needle assembly of FIG. 1in the protection position of FIG. 2.

FIG. 12 is a side cross-sectional view of the needle assembly of FIG. 1in the insertion position of FIG. 1.

FIG. 13 is a side cross-sectional view of the needle assembly of FIG. 1in the protection position of FIG. 2.

FIG. 14 is a perspective view of an alternate embodiment of the needleassembly of the present invention in the insertion position.

FIG. 15 is a perspective view of the needle assembly of FIG. 14 in theprotection position.

FIG. 16 is a perspective view of the upper portion of the needleassembly of FIG. 14 with an attached collapsible reservoir.

FIG. 17 is a view of the lower portion of the needle assembly of FIG.14.

FIG. 18 is a perspective view of an alternate embodiment of the needleassembly of the present invention.

FIG. 19 is a bottom view of the needle assembly of FIG. 18.

FIG. 20 is a front view of the needle assembly of FIG. 18.

FIG. 21 is a side view of the needle assembly of FIG. 18.

FIG. 22 is an exploded view of the needle assembly of FIG. 18.

FIG. 23 is side cross-sectional view of the needle assembly of FIG. 18in the insertion position.

FIG. 24 is a side cross-sectional view of the needle assembly of FIG. 18in the protection position.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to thedrawings, in which like elements in different drawings are identicallynumbered. The drawings, which are not necessarily to scale, depictselected preferred embodiments and are not intended to limit the scopeof the invention. In particular, although the examples provided hereinare related to use of the described embodiments with an implantedvascular access port, it is contemplated that the positive flushingfeature could be used with other medical devices to avert negativepressures upon the removal of needles or other medical equipment from asealed system.

The detailed description illustrates by way of example, not by way oflimitation, the principles of the invention. This description willclearly enable one skilled in the art to make and use the invention, anddescribes several embodiments, adaptations, variations, alternatives anduses of the invention, including what is presently believed to be thebest mode of carrying out the invention.

In a first embodiment of the present invention, a safety needle assemblywith positive flushing mechanism 10 is shown in FIG. 1. The assembly 10is shown in the insertion or use position, ready for insertion into theseptum of an implanted vascular access port within a patient (notshown). The assembly 10 has three main components: a body, having a maleportion 20 and a female portion 30, a base 40 and a needle 80. The maleportion 20 is attachable to an extension tubing set for delivery of afluid through the body to the needle 80, where it is dispensed into thevascular access port. The male portion 20 and female portion 30 arecollapsible so that following delivery of the fluid to the vascularaccess port, the fluid within the body can be expunged as the needle iswithdrawn from the vascular access port, creating a positive flush. Thecollapsible action of the body during withdrawal of the needle 80 occurssimultaneously with mechanical precision as will be explained in detailbelow. The body and base 40 in this embodiment are constructed ofplastic, although certainly a number of different materials arepossible, as one of skill in the art would appreciate. The needle 80 hasa non-coring configuration, meaning that the tip 82 of the needle isangularly bent with respect to the longitudinal axis of the needle shank84.

FIG. 2 illustrates the assembly 10 in the protection or safe position,following withdrawal of the needle 80 from the vascular access port.From this view, the various elements of the base 40 can be seen. Base 40includes a contact patch 42, which is a flat portion that rests againstthe skin of a patient and can be held thereto by a clinician as hebegins withdrawal of the needle 80 from the vascular access port tomaintain the position of the assembly 10 and allow for smooth mechanicalinteraction of the various components in providing the inventivepositive flush. While the contact patch 42 is shown in a flat, roundedconfiguration, there are various other configurations that would equallybe within the scope of the present invention, including configurationsthat take into account the particular area and contour of the body onwhich the assembly 10 is to be mounted so that the assembly 10 liesflush against the patient. In such an embodiment, the contact patch 42would not have to be flat and instead could assume a variety of shapesas one of skill in the art should appreciate. It is noted that the useof a contact patch is advantageous in stabilizing the needle assembly 10and facilitating smooth withdrawal of the needle, particularly in theevent that the needle is stuck in the vascular access port or isotherwise difficult to remove.

Attached to the contact patch 42 is an arm 44. The arm 44 is eitherpermanently connected to the contact patch 42 (through gluing, welding,etc.) at a first end 48 or is constructed as a single piece “livinghinge” design. Opposite first end 48, the arm has a snap-fit interface46 for unidirectional connection to the male portion 20 of the body. Theunidirectional connection permits division between components (i.e.,manufacturability) while ensuring that the safety feature of the designis not defeated. Integrally connected to the arm 44 and adjacent thefirst end 48 thereof is a hinge 50 for connection to the female portion20 of the body to serve as a range of motion limit, which prevents overextension of the safety feature. The hinge 50 can be seen in more detailin FIGS. 3 and 4, showing the base 40 in the insertion position andprotection position without the body for a clear view of the elements ofthe base 40 and their relative positions and movement in the twoindicated positions of the assembly 10. Referring first to FIG. 3, thebase 40 is shown in the insertion position, with arm 44 substantiallyflat against the contact patch 42 and hinge 50 folded within aperture 45of arm 44. Pin interface 58 of the hinge 50 for connection to the femaleportion 20 is shown in its attached position.

FIG. 4 illustrates the base 40 in the protection position as both thearm 44 and the hinge 50 are moved in an upward direction with respect tothe contact patch, which remains stationary against the skin of thepatient. In this position, the full length of the hinge 50 can be seen,including an upper and lower portion connected by a hinge point 56. Alsoseen is a needle housing 60, positioned on the contact patch 48 abuttingthe first end 48 of the arm 44. the needle housing 60 has an open shaft66 therethrough to permit passage of the needle 80. The needle housing60 traps the needle therein when the assembly 10 is in the protectionposition, thereby providing a secondary locking mechanism to complementthe primary locking mechanism provided by the body.

Referring to FIGS. 5A and 5B, one embodiment of needle housing 60 isprovided. In this embodiment, the needle 80 passes through the needlehousing shaft 66 and the distal opening 62 of the needle housing 60 asshown in FIG. 5A in the insertion position. The distal opening 62 of theneedle housing 60 is smaller in diameter than the needle housing shaft66, creating a ledge 64. Due to the non-coring configuration of needle80 (where needle tip 82 is offset from needle shank 84) and the factthat the distal opening 62 is closely sized to the diameter of theneedle shank 84, when the needle tip 82 passes through the distalopening 62 in a proximal direction, the tip 82 is deflected so that itmay pass through the distal opening 62. As the needle 80 is drawnfurther in a proximal direction, the needle tip 82 enters the largerdiameter needle shaft 66 where it returns to its initial axial positionwith respect to the distal opening 62 as shown in FIG. 5B in theprotection position. This action results in the needle tip 82 beingbiased within the needle shaft 66, as movement in the distal directionis prevented by ledge 64. Variations to this embodiment include wedge orcone shaped features on the ledge 64 to further assist in preventingdistal movement of the needle tip 82 through the distal opening 62.Other embodiments which would be apparent to one of skill in the art arealso possible, depending on the shape and size of the needle.

Referring now to FIGS. 6-9, the male portion 20 and the female portion30 of the body are shown separately. In FIGS. 6 and 7, the male portion20 is shown from a bottom (FIG. 6) and a top (FIG. 7) viewpoint. Themale portion 20 has an extension leg tubing connector 26, a plunger 22and two guide pins 23. The guide pins 23 are positioned on each side ofthe plunger 22 and contain at their distal end knobs 24 that act as aclosure locking mechanism when received in recesses within the femaleportion 30. The knobs 24 have an expanded and a contracted diameter,which is created as shown in FIG. 7 by having four sections separated attheir distal end, but joined at their proximal end at neck 25. Thus,with no radial pressure exerted thereon, the knobs 24 assume an expandeddiameter approximately equivalent to the diameter of the guide pins 23.

However, under the force of radial pressure, for example exerted by anarrowing diameter, the four sections press together and thereby assumea contracted diameter that is smaller than the expanded diameter. Ofcourse, the knobs 24 could be configured in other ways as one of skillin the art should appreciate, which would also impart an expanded andcontracted diameter thereto based on the presence of an outside radialforce. It is important to note that the sectioned distal end of theknobs 24 are rounded and tapered while their proximal end connected tothe necks 25 is not. This configuration in conjunction with that of theproximal end of the female portion 30 produces the primary lockingmechanism of this embodiment as explained in more detail below.

From the bottom view in FIG. 6, a snap groove 28 can be seen, which isconfigured to receive the snap-fit interface 46 of the arm 44. From thetop view in FIG. 7, fluid passage opening 29 can be seen through thedistal end of the plunger 22, where fluid flows to the female portion30. The plunger 22 has an O-ring around its distal end to provideleak-resistance. Fluid passage 27 fluidly connects fluid passage opening29 with an opening in the extension leg tubing connector 26 (see FIG.10). In both views, a finger rest 21 can be seen on the proximal end ofthe male portion 20 to facilitate manual collapse of the male portion 20into the female portion 30 by the clinician.

In FIGS. 8 and 9, the female portion 30 is shown from a proximal (FIG.8) and a distal (FIG. 9) viewpoint. The female portion 30 contains aplunger receptacle 32 and guide pin receptacles 34, sized to slidinglyreceive the plunger 22 and guide pins 23 of the male portion 20 througha proximal end thereof. At a distal end of the female portion 30, afinger rest 31 is positioned, similar to finger rest 21 of the maleportion 20, to facilitate collapse. From the distal viewpoint, lockingchambers 36 can be seen that are configured to receive the knobs 24 ofthe guide pins 23 so that subsequent movement of the guide pins 23 issubstantially prevented. The locking chambers 36 have a diameterequivalent to the guide pin receptacles 34, but include a narrowedregion at the proximal end thereof to force the knobs 24 of the maleportion 20 into their contracted diameter. After the knobs 24 movedistal to the narrowed region and into the locking chambers 36, theknobs 24 resume their expanded diameter (due to the removal of pressurethereon) and are thereby “trapped” in the locking chamber as thenarrowed region prevents proximal movement thereof due to thenon-tapered configuration of the proximal end of the knobs 24.

Also shown in FIG. 9 is a needle mounting region 35, where a proximalend of the needle 86 (see FIG. 12) is held, and which enables fluidconnection of the proximal end of the needle 86 to the plungerreceptacle 32. While the mounting region 35 is shown as an arched areasized to frictionally hold the proximal end of the needle 86, which isangularly positioned relative to the needle shank 84, certainly manyother configurations are possible, depending on the size and type ofneedle employed, which would equally be within the scope of the presentinvention. A mechanical interlock 37 is positioned on the proximal endof the female portion 30 for releasable connection to a recess on thebase 40. The interlock 37 snaps into place when the assembly 10 is inthe insertion position to prevent accidental movement of the assembly 10during fluid delivery to a vascular access port. When it is desired tomove the assembly into the protection position, the interlock 37 can bemanually moved out of the recess. Of course, it should be appreciatedthat numerous types of releasable mechanisms would equally be desirableand are therefore contemplated to be within the scope of the presentinvention, including an embodiment wherein the recess was positioned onthe female portion 30 and the mechanical interlock was positioned on thebase 40.

Turning now to FIGS. 10-11, the assembly 10 is shown in the insertionand protection positions with the body shown in cross-section toillustrate the action of the plunger 22 and the guide pins 23.Initially, in the insertion position, the male portion 20 is in anuncollapsed state with respect to the female portion 30 so that fluidpassing through the extension leg tubing 26, into the fluid passage 27and through the fluid passage opening 29 collects in the plungerreceptacle 32 before flowing into the proximal end of the needle 86. Asthe assembly 10 is moved from the insertion position to the protectionposition, the plunger 22 and guide pins 23 of the male portion 20 aremoved through the respective receptacles 32 and 34 of the female portion30 as shown in FIG. 11. As explained above, when the knobs 24 on thedistal ends of the guide pins 23 pass over the narrowed region of thelocking chambers 36, the knobs 24 are prevented from moving proximallyback into the guide pin receptacles 34, thereby providing a primarylocking mechanism for the assembly 10.

A use of the assembly 10 will be explained with reference to FIGS. 12and 13, which show a side cross-sectional view of the assembly 10. Thefully assembled assembly 10 is prepared for insertion into a vascularaccess port by first removing a protective sleeve over the needle (notshown). The exact location of the vascular access port and, inparticular, the septum through which the needle of the assembly 10 is tobe placed is identified by the clinician and by grasping the assembly 10on either side thereof in the insertion position, the needle is pressedthrough the patient's skin and into the septum of the vascular accessport. At this time, the contact patch 42 should be flat against thepatient's skin and optionally can be secured thereto by utilizing tapeor other adhesive. Extension leg tubing, which has previously beenconnected to the extension leg tubing connector 26 (or alternatively isattached following securing the lower portion to the patient's skin), isattached to a fluid source, which pumps fluid in the form of a drug ormedicine through the extension leg tubing, into the fluid passage 27,through the plunger receptacle 32 and into the proximal end of theneedle 86, through the needle 80 and into the vascular access port (notshown).

When fluid delivery has been completed, the clinician clamps theextension leg tubing, removes the tape or adhesive (if any), unlocks themechanical interlock 37 from the recess in the base 40, places thefingers of one hand on the contact patch 42 and with the second handsqueezes the male portion 20 and female portion 30 together, utilizingrespective finger rests 21 and 31. By securing the needle assembly 10with one hand in contact with the contact patch, stability of theassembly 10 is ensured, which is particularly useful should the needle80 become stuck or otherwise prove difficult to remove from the vascularaccess port. As mentioned above, this occurrence often times results inaccidental needle sticks, which are prevented through the stableconfiguration of the described embodiment.

The squeezing together of the body causes simultaneous action inseparate parts of the assembly 10. With respect to the base 40, as themale portion 20 of the body moves toward the female portion 30, the arm44 is forced in an upward direction, which in turn carries the bodyupward, which moves the needle up and out of the vascular access port.With respect to the fluid in the body, as the male portion 20 of thebody moves toward the female portion 30, the plunger 22 expunges thefluid within the plunger receptacle 32 through the needle 80 as theneedle is moving out of the vascular access port. This action creates apositive flush whereby the volume of fluid being expunged simultaneousreplaces the volume of the needle in the reservoir of the vascularaccess port so that a negative pressure in the vascular access port isaverted. Ideally, the volume of the infusion fluid contained in the bodywould be greater than the volume of the. needle so that the infusionvolume to the port can be manipulated by changing the geometry of thearm 44. Also, typically the fluid flow rate from the body during thepositive flushing action is greater than the normal fluid flow ratethrough the assembly in the insertion position.

With respect to the body, the squeezing together of the male portion 20and the female portion 30 eventually causes the knobs 24 on the distalends of the guide pins 23 to move into the locking chambers 36 therebypreventing further relative movement of the male and female portions. Atthe same time, the needle tip 82 passes through the distal opening 62and into the needle housing shaft 66 where it is biased therein,prevented from distal movement by ledge 64. Thus, in the protectionposition shown in FIG. 13, the assembly 10 is held in place by both aprimary and secondary locking mechanism.

FIGS. 14-17 illustrate another embodiment of the present invention.Winged assembly 100 contains three primary components: a needle 80, aneedle housing, having an upper portion 110 and a lower portion 120, anda collapsible reservoir 150. The winged assembly 100 is shown in FIG. 14in the insertion position and in FIG. 15 in the protection position.Referring to FIG. 16, the upper portion 110 of the housing is shownwithout the lower portion 120 attached. The needle 80 is attached to thefront 114 of the upper portion through an opening or groove therein withthe use of adhesives, friction fit, mechanical means or some combinationthereof. Needle 80 may or may not have a proximal end which is angularlypositioned with respect to the shank thereof. The proximal end of theneedle is fluidly connected to the collapsible reservoir 150, which isdisposed within the upper portion 110 of the housing. The collapsiblereservoir 150 is configured to be collapsible in the presence ofexternally exerted force and is so positioned within the upper portion110 of the housing. In particular, the collapsible reservoir 150 isadhered to only a single horizontal surface of the upper portion 110 sothat the vertical surfaces of the collapsible reservoir are allowed tocollapse in a uniform manner.

At the rear of the upper portion 110, a connector (not shown) isattached to enable connection to an extension tubing, the connectorbeing in fluid communication with the collapsible reservoir 150. Acrossthe top region of the upper portion 110, opposing wings 116 span tofacilitate grasping and movement of the winged assembly 100. At the baseof the upper portion 110, below the attached collapsible reservoir 150,a portion containing four grooves 113 is positioned, which permit asnap-fit of the lower portion 120 therein, positive locking the lowerportion 120 to the upper portion 110. Attached to the bottom of theupper portion 110 is a stiffening rib 112, which acts to providestructural support to the winged assembly 100 and which releasably locksthe winged assembly 100 in the insertion position by snapping intogrooves 142 in the lower portion 120 (see FIG. 17).

Referring now to FIG. 17, the lower portion 120 is shown in isolation.The lower portion contains four panels that function through the use ofliving hinges therebetween. The four panels are really two panels thatmirror each other, separated by a needle housing 140 and grooves 142that interlock with the stiffening rib 112. The outer panels 122, 124contain rods 132 that snap-fit within the grooves 113. Between the rods132 are extensions 130, which press against the collapsible reservoir150 as the winged assembly moves from an insertion position to aprotection position, thereby collapsing the collapsible reservoir 150and expunging the fluid therefrom. Below the extensions are windows 134that align with protrusions 136 on adjacent inner panels 126, 128. Onthe sides of the outer panels 122, 124 are recesses 131, which are sizedto receive locking sections 133 on the adjacent inner panels 126, 128 toreleasably lock the winged assembly 100 in the insertion position.

In a separate locking mechanism, the protrusions 136 of the inner panels126, 128 mate with one another in the protection position through thecomplementary button/detent thereon (FIG. 17 shows button 138 onprotrusion 136, whereas FIG. 14 reveals the detent on the opposingprotrusion 136) to permanently lock the winged assembly 100 in theprotection position. Positioned adjacent the protrusions 136 areapertures 137 to allow full movement of the opposing protrusion 136 asthe winged assembly 100 is moved into the protection position. While theprotrusions 136 are illustrated as being offset from one another formating purposes, it is envisioned that alternate embodiments would haveother types of interlocking mechanisms that were not so offset andrather provided a positive locking feature by snapping together orotherwise permanently locking. Between the inner panels 126, 128 is aneedle housing 140 that operates similarly to the needle housing 60 asexplained above to prevent movement of the needle in a distal directiononce the needle tip has passed into the needle shaft and is biased toits normal position.

Referring back to FIGS. 14 and 15, the operation of the winged assembly100 is initiated by the clinician by removing a protective needle sheath(not shown) from the needle and grasping the wings 116 with one hand asthe winged assembly 100 is locked in the insertion position (FIG. 14).The clinician squeezes the wings 116 together to grip the wingedassembly 100 and presses the needle 80 into a patient's skin and into animplanted vascular access port. The inner panels 126, 128 of the lowerportion 120, lying substantially flat against the patient's skin, canthen be secured thereto for delivery of the fluid by applying tape orother type of adhesive to the lower portion 120 (for example, tapingover the outer panels 122, 124). An extension tubing set, previouslyattached to the connector at the rear 114 of the upper portion 110 (oralternatively attached following securing the lower portion to thepatient's skin), is itself connected to a fluid source, which pumpsfluid through the connector, into the collapsible reservoir 150, throughthe needle 80 and into the vascular access port.

When delivery of the fluid is completed, the extension tubing is clampedand the tape or adhesive (if any) is removed. The clinician with onehand squeezes the lower portion 120 together, causing the lockingsections 133 to disengage from the recesses 131 and the inner panels126, 128 to align longitudinally with the outer panels 122, 124 as shownin FIG. 15. As the panels straighten with respect to one another, theneedle is withdrawn from the vascular access port. It is noted that thisconfiguration prevents accidental needle sticks due to the fact that theneedle is never exposed outside of the body. As soon as the needle exitsthe skin, it is enveloped by the lower portion 120.

Simultaneously to the needle withdrawal, the extensions 130 on the outerpanels 122, 124 press into the collapsible reservoir 150 causing it tocollapse and expunge fluid therein through the needle 80 and into thevascular access port as the needle moves outward. This simultaneousaction produces a positive flush whereby the volume of fluid beingexpunged simultaneous replaces the volume of the needle in the reservoirof the vascular access port so that a negative pressure in the vascularaccess port is averted. As the panels straighten, the protrusions 136press together, the complimentary button/detent 138 positively andpermanently locking together. At the same time, the needle tip 82 passesthrough a distal opening of the needle housing 140 and into a needlehousing shaft where it is biased therein, prevented from distal movementby a ledge. Thus, in the protection position shown in FIG. 15, thewinged assembly 100 is held in place by both a primary and secondarylocking mechanism.

In another embodiment of the present invention, illustrated by FIGS.18-24, a balloon and compression plate combination acts as a mechanismby which a positive flush is created. Referring to FIGS. 18-21, variousviews of a needle assembly 200 are illustrated. Needle assembly 200includes a wing base 210 onto which is mounted a handle 220, havingseparate left 222 and right 224 halves that interlock with one anotherwhen assembled. Below the wing base 210 is a support structure 240,which has an opening 248 for needle 80. As best seen in FIG. 20, boththe handle 220 and the wing base 210 have contoured surfaces for fingerplacements along with respective ridges 226 and 218 for gripping. Thecontoured surface 216 of wing base 210 comprises a raised portion ateach opposing end. These features provide ease of use and protectagainst slippage. Needle 80 is fluidly connected to tail 252, which isconfigured for connection to extension leg tubing (not shown).

An exploded view of needle assembly 200 is illustrated in FIG. 22,showing the separate parts prior to assembly. The support structure 240is assembled through the bottom of the wing base 210 through fouropenings 212, each of which accommodates a leg 242 of the supportstructure. The legs 242 are each configured with a first notched section244 and a second notched section 246, which serve different purposes aswill be explained more fully below. Support structure 240 and wing base210 each contain an opening 248, 214 that are aligned for receiving aprotection sleeve 230 and the needle 80. The protection sleeve 230 ismade of a material thick and/or tough enough so that the needle 80cannot penetrate through in the protection position, such as nylon,though certainly a number of materials are certainly possible. Theprotection sleeve 230 has a proximal portion 232, having an increasedradius for bonding between the support structure 240 and the wing base210. The protection sleeve 230 also has a distal portion 234 with atapered configuration for ease of insertion within the body of apatient.

The left 222 and right 224 halves of handle 220 snap together on top ofthe wing base 210, enclosing therein a proximal end 86 of the needle 80around which a balloon extension 250 is fitted. The balloon extension250 holds a volume of fluid for the positive flushing feature asdescribed in detail below. Positioned above the balloon extension 250 isa compression plate 260, which acts to press the fluid out of theballoon extension 250 as the needle assembly is moved from the insertionposition to the protection position. It should be appreciated thatalthough a balloon extension is illustrated, many possibilities existfor a collapsible or compressible member that could contain within it avolume of fluid and which would collapse upon pressure from an externalsource. In addition, it should be noted that balloon extension 250 couldbe made of various materials (for example, silicone or polyurethane),which have the desired properties of ruggedness, attachability andcollapsibility so that any problems associated with bursting orloosening from the needle are avoided.

FIG. 23 illustrates, in cross-section, the needle assembly 200 in theinsertion position. With reference to this view, the assembly of theneedle assembly 200 will be explained, although certainly other mannersof assembly are also possible with respect to chemical or mechanicalbonds. From this view, the interlocking features of the handle 220 canclearly be seen. As shown in FIG. 22, the right half 224 of the handle220 has holes 225 in the upper corners thereof to receive pins 227positioned on the upper corners of the left half of the handle 220,although certainly the holes 225 and pins 227 could be reversed. Thehandle 220 also includes interlocking tabs 229 positioned on the sidesof each half 222, 224 near the lower corners thereof, which are receivedin corresponding slots on the opposing half. These interlocking featuresare intended to be one-way or permanent so that convenience ofmanufacture can be maintained without sacrificing safety, although it ispossible that releasable locks would be desired in certain situations.Moreover, while interlocking features have been specifically described,it should be appreciated that various possibilities exist to lock ahandle around certain internal parts that would equally be within thescope of the present invention.

Because of the separate halves of the handle 220, assembly of thecompression plate 260 can be accomplished without any special tools asthe plate 260 is merely slid into the notched sections 248 on each ofthe four legs 242 of the support structure 240 over the balloonextension 250 after it has been positioned against the lower portion ofthe handle 220. It should be noted that the handle 220 envelopes thecompression plate 260 and the balloon extension 250, but is not attachedto the wing base 210. The support structure 240 is chemically bonded tothe bottom of the wing base 210 to hold the aforementioned components inplace with respect to one another. The balloon extension 250 is bondedto the proximal end 84 of the needle 80 and has a tail 252 extending outof an opening in the back of the handle 220.

Referring now to FIG. 24, the needle assembly 220 is illustrated in aprotection position, showing the interaction between various partsthereof as the needle 80 is withdrawn from a vascular access port (notshown). Similar to embodiments described above, the needle assembly 200in the insertion position lies on top of a patient's skin, the needle 80inserted into a vascular access port implanted below the patient's skin.The wing base 210 with the support structure 240 lie flush against thepatient's skin. Upon delivery of drug or other medicant to the port, thephysician places the index finger and thumb of one hand onto the wingbase 210, pressing it against the patient's skin, while grasping thehandle 220 with the free hand and pulling it in an upward direction. Thehandle 220 slides along the legs 242, which remain stationary, beingbonded to the wing base 210. The legs 242 are tapered, causing them tobend as the handle 220 is pulled upward, which creates resistance. Theresistance is useful in preventing a withdraw that is too quick, whichcould potentially lead to problems.

The upward action of the handle 220 removes the needle 80 from thevascular access port while simultaneously flushing fluid containedwithin the balloon extension 250 through the distal needle tip 82,thereby replacing the volume of the needle in the reservoir of thevascular access port with the fluid contained within the balloonextension 250 so that a negative pressure in the vascular access port isaverted. A positive flush is created, as shown in FIG. 24, by the actionof the compression plate 260 against the balloon extension 250.Specifically, as the handle 220 is pulled upward with respect to thewing base 210, the balloon extension 250, which lies between the base ofthe handle 220 and the compression plate 260, is compressed as thecompression plate 260 remains stationary with respect to the handle 220.More particularly, the compression plate 260 is held in place by thelegs of the support structure 240 and is not attached to the handle 220,so that movement of the handle 220 causes the compression of the balloonextension 250.

It should be noted that while a compression plate is described, thepresent invention would also encompass an embodiment where thecompression of the compressible member, such as balloon extension 250,takes place via configurations of the internal portions of the handle orvia configurations of the support structure that reaches into thehandle. Alternatively, other housing configurations could be imaginedwithin the scope of the present invention that would cause compressionof the compressible member upon relative movement between the housingand a base.

Simultaneous to the positive flush taking place, the needle assembly 200locks into a safety position in two respects. First, the needle tip 82enters the protection sleeve 230 as the handle 220 is moved upward withrespect to the wing base 210. When the handle 220 reaches the positionof the first notched section 246 of the legs 242 of the support section240, the lower portion of the handle 220 locks into place, snappingaudibly in the process to provide a positive indication to the physicianto cease withdraw. This is the primary locking mechanism for needleassembly 200. Due to the locking interaction between the handle and thelegs 242 of the support section 240, the balloon extension 250 isprevented from expanding upon release, which would cause backflow. Atthis locked position, the needle tip 82 is fully within the protectionsleeve 230, the tip coming into contact with the inner surface thereof,which prevents movement out of the sleeve. This secondary lockingmechanism ensures that the needle tip 82 is completely covered by theprotection sleeve 230 to avoid accidental needle sticks.

The present invention has been described above in terms of certainpreferred embodiments so that an understanding of the present inventioncan be conveyed. However, there are many alternative arrangements for apositive flush mechanism not specifically described herein but withwhich the present invention is applicable. Although specific featureshave been provided, the safety needle with positive flush device of thepresent invention would equally be embodied by other configurations notspecifically recited herein. The scope of the present invention shouldtherefore not be limited by the embodiments illustrated, but rather itshould be understood that the present invention has wide applicabilitywith respect to a positive flush system generally. All modifications,variations, or equivalent elements and implementations that are withinthe scope of the appended claims should therefore be considered withinthe scope of the invention.

1. A safety needle assembly for use with a subcutaneously implantedvascular access port, comprising: a needle having a proximal end and adistal end; a body attached to and in fluid communication with theproximal end of the needle; and a base attached to the body; whereinmovement of the needle assembly from an insertion position to aprotection position expunges fluid from the body through the distal endof the needle, creating a positive flush.
 2. The needle assemblyaccording to claim 1, wherein the proximal end of the needle isangularly positioned relative to the distal end of the needle.
 3. Theneedle device according to claim 1, wherein said distal end of saidneedle has a non-coring configuration.
 4. The needle assembly accordingto claim 1, wherein said base comprises a needle housing that surroundsthe distal end of said needle and prevents movement thereof in a distaldirection when the needle assembly is in the protection position.
 5. Theneedle assembly according to claim 1, wherein said base comprises acontact patch that maintains contact with a patient's skin duringmovement from the insertion position to the protection position.
 6. Theneedle assembly according to claim 5, wherein said contact patchconforms to the contour of the patient.
 7. The needle assembly accordingto claim 5, wherein said base further comprises an arm and a hinge,being respectively attached to an opposite end of said body.
 8. Theneedle assembly according to claim 1, wherein said body comprises afemale portion and a male portion that collapse together upon movementfrom the insertion position to the protection position.
 9. The needleassembly according to claim 8, wherein said male portion comprises aplunger element that expunges fluid from said female member when theneedle assembly is moved from the insertion position to the protectionposition.
 10. The needle assembly according to claim 8, wherein saidmale portion comprises at least one guide pin having at its distal end alocking portion.
 11. The needle assembly according to claim 10, whereinsaid female portion comprises a guide pin receptacle having a lockingchamber that receives said locking portion of said guide pin, therebypreventing relative movement of said male portion.
 12. The needleassembly according to claim 11, wherein said locking portion comprisesan expanded diameter and a contracted diameter.
 13. The needle assemblyaccording to claim 12, wherein said locking chamber comprises a narrowedregion that exerts external pressure on said locking portion, forcingsaid locking portion into its contracted diameter.
 14. The needleassembly according to claim 8, wherein said female portion comprises areleasable interlock member that releasably locks said body to said basewhen the needle assembly is in the insertion position.
 15. The needleassembly according to claim 8, wherein said base comprises a contactpatch that maintains contact with a patient's skin during movement fromthe insertion position to the protection position.
 16. The needleassembly according to claim 15, wherein said contact patch comprisesneedle housing that surrounds the distal end of said needle and preventsmovement thereof in a distal direction when the needle assembly is inthe protection position.
 17. The needle assembly according to claim 16,wherein said base further comprises an arm and a hinge, said arm beingattached at one end to said male portion and at an opposite end to saidfirst component, said hinge being attached at one end to said arm and atan opposite end to said female member.
 18. A needle device for use witha subcutaneously implanted vascular access port, comprising: a needlehaving a proximal end and a distal end; a housing attached to saidproximal end of said needle, comprising a lower portion and an upperportion, said lower portion being movable from an insertion position toa protection position, said upper portion being graspable to facilitatepositioning of said needle device; and a collapsible reservoir disposedbetween said upper and lower portions of said housing and in fluidcommunication with said fluid flow path of said needle.
 19. The needledevice according to claim 18, wherein said proximal end of said needleis angularly positioned relative to said distal end.
 20. The needledevice according to claim 18, wherein said distal end of said needle hasa non-coring configuration.
 21. The needle device according to claim 18,wherein said lower portion comprises at least one extension positionedadjacent said collapsible reservoir, wherein said extension engages saidcollapsible reservoir when said lower portion is moved from theinsertion position to the protection position, thereby expunging fluidfrom said collapsible reservoir.
 22. The needle device according toclaim 18, wherein said lower portion comprises a releasable lockingmechanism that releasably locks said lower portion in the insertionposition.
 23. The needle device according to claim 18, wherein saidlower portion comprises a permanent locking mechanism for permanentlylocking said lower portion in the protection position.
 24. The needledevice according to claim 18, wherein said lower portion comprises anintegral hinged assembly having a plurality of connected sections. 25.The needle device according to claim 24, wherein said hinged assemblycomprises at least one extension positioned adjacent said collapsiblereservoir, wherein said extension engages said collapsible reservoirwhen said lower portion is moved from the insertion position to theprotection position, thereby expunging fluid from said collapsiblereservoir.
 26. The needle device according to claim 24, wherein saidhinged assembly comprises a releasable locking mechanism that releasablylocks said lower portion in the insertion position.
 27. The needledevice according to claim 26, wherein said releasable locking mechanismcomprises a first locking element positioned on the interior of at leastone of said sections in alignment with a corresponding second lockingelement positioned on an adjacent section when said lower portion is inthe insertion position.
 28. The needle device according to claim 24,wherein said hinged assembly comprises a permanent locking mechanism forpermanently locking said lower portion in the protection position. 29.The needle device according to claim 28, wherein said permanent lockingmechanism comprises two protrusions positioned on the interior adjacentinner sections, said protrusions being configured to lock together inthe protection position.
 30. The needle device according to claim 18,wherein said lower portion comprises an integral hinged assembly havingfour connected sections, wherein a first and fourth section areconfigured for attachment to said upper portion and wherein a second andthird section are configured for locking engagement with one anotherwhen in the protection position.
 31. The needle device according toclaim 30, wherein said second and third section each have a protrusionon an interior thereof, wherein said protrusions on said second andthird sections are configured for locking engagement when the needledevice is in the protection position.
 32. The needle device according toclaim 31, wherein said first section has an opening in alignment withsaid protrusion on said second section for receipt therethrough whensaid lower portion is in the insertion position and wherein said fourthsection has an opening in alignment with said protrusion on said thirdsection for receipt therethrough when said lower portion is in theinsertion position.
 33. The needle device according to claim 30, whereinat least one of said first and fourth sections comprises a first lockingelement and wherein at least one of said second and third sectionscomprises a second locking element, said first and second lockingelements being configured for releasably locking said lower portion inthe insertion position.
 34. The needle device according to claim 30,wherein said first and fourth sections each comprise an extensionportion wherein said extension portions press against said collapsiblereservoir when said lower portion is moved from said insertion positionto said protection position.
 35. A safety needle assembly, comprising: aneedle having a proximal end and a distal end; a compressible memberconnected to a proximal end of said needle and in fluid communicationtherewith; a base having an opening for receiving said needle; a bodysurrounding said compressible member and movable with respect to saidbase; wherein movement of said needle assembly from an insertionposition to a protection position expunges fluid from the compressiblemember through the distal end of the needle, creating a positive flush.36. The needle assembly according to claim 35, wherein the proximal endof the needle is angularly positioned relative to the distal end of theneedle.
 37. The needle device according to claim 35, wherein said distalend of said needle has a non-coring configuration.
 38. The needle deviceaccording to claim 35, wherein the compressible member comprises aballoon having a capacity to hold a volume of fluid.
 39. The needledevice according to claim 35, wherein said base is positioned under saidbody, said base comprising a winged member configured to liesubstantially flat against a surface.
 40. The needle device according toclaim 39, wherein said winged member further comprises a contouredsection.
 41. The needle device according to claim 40, wherein saidcontoured section comprises gripping ridges.
 42. The needle deviceaccording to claim 39, wherein said base further comprises a supportstructure.
 43. The needle device according to claim 42, wherein saidsupport structure has an extending portion that extends through saidwinged member and into said body.
 44. The needle device according toclaim 43, wherein said extending portion is configured for holding acompression member.
 45. The needle device according to claim 44, whereinsaid compressible member is positioned between said compression memberand said body.
 46. The needle device according to claim 43, wherein saidextending portion comprises a locking section, wherein movement to theprotection position permanently locks the body to the extending portion.47. The needle device according to claim 43, wherein said extendingportion comprises a plurality of legs.
 48. The needle device accordingto claim 47, wherein said legs are tapered.
 49. The needle deviceaccording to claim 48, wherein said legs comprise a first notchedsection, configured to receive a portion of said body therein when saidneedle assembly is in the protection position.
 50. The needle deviceaccording to claim 48, wherein said legs comprise a second notchedsection, configured to receive a compression member therein.
 51. Theneedle device according to claim 35, wherein said body comprisesseparate halves that permanently lock together.
 52. The needle deviceaccording to claim 35, wherein said body comprises a contoured outersurface.
 53. The needle device according to claim 52, wherein saidcontoured outer surface comprises gripping ridges.
 54. The needle deviceaccording to claim 35, further comprising a compression member, whereinmovement from the insertion position to the protection position forcessaid compression member against said compressible member.
 55. The needledevice according to claim 35, further comprising a protection sleevesurrounding a portion of said needle, wherein a needle tip of saidneedle is uncovered by said protection sleeve when said needle assemblyis in the insertion position and wherein said needle tip is covered bysaid protection sleeve when said needle assembly is in the protectionposition.
 56. The needle device according to claim 55, wherein saidneedle tip is biased against movement out of said protection sleeve whensaid needle assembly is in said protection position.
 57. A method ofsupplying fluid to a vascular access port, comprising: providing aneedle assembly comprising a needle and a positive flushing mechanism;inserting said needle into said vascular access port; delivering fluidto said vascular access port; removing said needle from said vascularaccess port; wherein said positive flushing mechanism is engaged,sending a volume of fluid through said needle before said needlecompletely exits said port.
 58. A method for preventing a negativepressure within a vascular access port upon removal of a needletherefrom, comprising: activating a positive flushing mechanismcomprising a fluid-holding member, wherein a volume of fluid issimultaneously released from said member through a needle tip of saidneedle when said needle tip is withdrawn from said vascular access port.